Sure. You can run 87 and not have any problems with knock. It is all in the tune. Will you be able to run 25 pounds? Most likely not. 20? Probably so. Start off slow and up the boost as the knock allows. I run 91 because that is all they sell around my house so that's what I have it tuned for. I, at the moment, have maxed out my turbo and am tuning on the timing.
Just be careful as there is marginal room for error...
Jason